What overhead share should I use?

PROFINET planning rule of thumb is to keep cyclic traffic below 50 percent of link capacity. EtherNet/IP is similar. MQTT non-cyclic traffic adds on top; profile your link.

Why model uptime as well?

A 1 Gbps link delivers far less if the switch port flaps. Including uptime keeps the headroom number honest.

Should I size to peak or average?

Peak. Industrial protocols are bursty; sizing to average underestimates headroom needs and causes recurring slowdowns.

How do I model a redundant ring?

Run the calculator on the working path. The redundant path provides resilience but does not add usable bandwidth in normal operation.

IIoT, SCADA & Edge Connectivity calculator

Industrial Network Bandwidth Calculator

Estimate usable industrial network bandwidth on a switch link. Enter raw link speed (typical 100 or 1000 Mbps), planned operating share of the period, link uptime, and the share of bandwidth left after control protocol overhead, management traffic, and headroom for spikes. The calculator returns gross Mbps available, usable Mbps, and overhead loss.

What this calculator does

Estimate available industrial network bandwidth from raw link speed in Mbps, planned operating share of the period, link uptime, and the share of bandwidth left after control protocol and management overhead.
Use it when an OT network engineer is sizing whether a 100 Mbps or 1 Gbps switch ring can carry the planned PROFINET, EtherNet/IP, MQTT, and management traffic without saturation.
It returns the usable Mbps on an industrial network link after uptime loss and protocol overhead, against the raw link speed.

Formula used

Gross network bandwidth = raw link speed × planned operating share
Usable network bandwidth = gross bandwidth × link uptime × share after overhead

Inputs explained

Raw link speed: Use the switch port speed (100 or 1000 Mbps for typical industrial Ethernet, 10 Gbps for backbone uplinks).
Planned operating share: Use 1 for continuous links. Use a fraction if the link is only active some of the time (uncommon for industrial).
Link uptime: Use the share of the period the link was up (typical 99.9+ percent on a healthy industrial Ethernet).
Bandwidth left after protocol and management overhead: Use the share of bandwidth left after PROFINET RT, EtherNet/IP, MQTT, and management traffic (PROFINET planning rule of thumb is 50 percent left for spikes; EtherNet/IP is similar).

How to use the result

Use it before adding cyclic PROFINET I/O, MQTT publishers, or video traffic to a link, or when sizing a switch ring upgrade.
It is link-level. It does not capture switch backplane bottleneck, VLAN trunk congestion, or per-stream QoS issues; profile a real packet capture before final design.

Common questions

What overhead share should I use? PROFINET planning rule of thumb is to keep cyclic traffic below 50 percent of link capacity. EtherNet/IP is similar. MQTT non-cyclic traffic adds on top; profile your link.
Why model uptime as well? A 1 Gbps link delivers far less if the switch port flaps. Including uptime keeps the headroom number honest.
Should I size to peak or average? Peak. Industrial protocols are bursty; sizing to average underestimates headroom needs and causes recurring slowdowns.
How do I model a redundant ring? Run the calculator on the working path. The redundant path provides resilience but does not add usable bandwidth in normal operation.

Last reviewed 2026-05-12.